Production of nearly monodisperse Fe3O4 and Fe@Fe3O4 nanoparticles in aqueous medium and their surface modification for biomedical applications

Iron (Fe)-based nanoparticles are extremely valuable in biomedical applications owing to their low toxicity and high magnetization values at room temperature. In this study, we synthesized nearly monodisperse iron oxide (Fe 3 O 4 ) and Fe@Fe 3 O 4 (core: Fe, shell: Fe 3 O[Formula: see text] nanoparticles in aqueous medium under argon flow and then, coated them with various biocompatible ligands and silica. In this study, eight types of surface-modified nanoparticles were investigated, namely, Fe 3 O 4 @PAA (PAA = polyacrylic acid; [Formula: see text] of PAA = 5100 amu and 15,000 amu), Fe 3 O 4 @PAA–FA (FA = folic acid; [Formula: see text] of PAA = 5100 amu and 15,000 amu), Fe 3 O 4 @PEI–fluorescein (PEI = polyethylenimine; [Formula: see text] of PEI = 1300 amu), Fe@Fe 3 O 4 @PEI ([Formula: see text] of PEI = 10,000 amu), Fe 3 O 4 @SiO 2 and Fe@Fe 3 O 4 @SiO 2 nanoparticles. We characterized the prepared surface-modified nanoparticles using high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) absorption spectroscopy, a superconducting quantum interference device (SQUID), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy and confocal microscopy. Finally, we measured the cytotoxicity of the samples. The results indicate that the surface-modified nanoparticles are biocompatible and are potential candidates for various biomedical applications.